JP4947009B2 - Liquid ejection device - Google Patents

Description

The present invention relates to a liquid discharge equipment provided with a liquid discharge head for discharging a liquid from a plurality of nozzles.

  As an example of a liquid ejecting apparatus, an ink jet printer including an ink jet head that ejects ink from a plurality of nozzles is known. In Patent Document 1, as a maintenance method of an ink jet head in an ink jet printer, a pump that forcibly sends ink in an ink cartridge to an ink jet head is driven, and a purge operation is performed to discharge ink from all nozzles. A method of performing wiping to wipe the nozzle surface by moving the nozzle along the nozzle surface while contacting the nozzle surface is disclosed. By performing such maintenance, foreign matters such as ink and paper dust adhering to the nozzle surface are removed, and ink ejection characteristics are restored.

In the maintenance method as described above, the friction between the nozzle surface and the wiper can be reduced by the ink adhering to the nozzle surface by the purge operation. Therefore, it is possible to prevent the nozzle surface from being damaged by friction. In addition, if the ink is not ejected from the nozzles for a long time, the ink attached to the nozzle surface is in a thickened state, but the thickened ink is dissolved by performing a purge operation before wiping, Can be removed by wiping.
JP 2008-137351 A

  However, the above-described maintenance method has a problem that the ink consumption increases because the purge operation is performed in advance every time wiping is performed.

An object of the present invention is to provide a liquid discharge device that can reduce the consumption of the liquid.

A liquid discharge apparatus according to the present invention includes a liquid discharge head having a nozzle surface on which discharge ports of a plurality of nozzles are formed, an actuator that generates discharge energy for discharging liquid from the nozzle, and a wiper that wipes the nozzle surface. And determining means for determining whether or not a predetermined time has elapsed since the previous discharge of the liquid from the nozzle, and controlling the drive of the actuator so that a flushing operation for discharging a droplet from the nozzle is performed. Relative movement control that controls the driving of the relative movement mechanism, the relative movement mechanism that relatively moves the liquid ejection head and the wiper along the nozzle surface while the flushing control unit is opposed to the wiper and the nozzle surface. Means, a pressure application mechanism for applying pressure from the outside to the liquid in the liquid discharge head, and all the nozzles Purging liquid is discharged the and a pressure application control means for controlling the driving of the pressure application mechanism to be performed from. When the constant time Tokoro by said determining means is determined not to be passed in a state where the wiper is brought into contact with the nozzle surface, to perform the flushing operation by the control of the flushing control means In the state where the liquid droplets discharged from the nozzle are attached to the wiper and the wiper is in contact with the nozzle surface, the flushing operation is performed by the control of the flushing control means, and at the same time, the relative movement control is performed. Wiping to wipe the nozzle surface is performed by relatively moving the liquid discharge head and the wiper by means, and if it is determined that the predetermined time has passed, the purge is controlled by the pressure application control means After performing the operation, the wiping is performed under the control of the relative movement control means. The flushing control means is on the downstream side of the wiper relative movement direction with respect to the liquid ejection head from the contact position of the wiper on the nozzle surface and faces at least the wiper when viewed from a direction orthogonal to the nozzle surface. The liquid discharge amount per unit time from the one nozzle is larger than the liquid discharge amount per unit time from the one nozzle located upstream in the relative movement direction from the contact position. To control.

According to the above configuration, when a predetermined time has not elapsed since the previous liquid discharge, the nozzle that is discharged by the flushing operation and adhered to the wiper without performing a purge operation that consumes a relatively large amount of liquid. Friction between the surface and the wiper can be reduced. Therefore, it is possible to reduce the liquid consumption while preventing the nozzle surface from being damaged by friction with the wiper. On the other hand, when a predetermined time has elapsed since the previous discharge of the liquid, the thickened liquid can be dissolved by executing the purge operation. In addition, since the wiping is performed simultaneously with the flushing operation in a state where the wiper is in contact with the nozzle surface, the maintenance time can be shortened compared to the case where the liquid is attached to the wiper and the wiping is performed separately. . Furthermore, by controlling the discharge amount by the flushing control means, the wiper can be sufficiently lubricated downstream of the contact position in the relative movement direction, and the liquid consumption can be suppressed upstream of the contact position in the relative movement direction. The meniscus surface formed at the discharge port of the nozzle can be adjusted.

The flushing control means controls either the drive frequency of the actuator or the number of pulses in one printing cycle, so that the flushing control means is located downstream of the wiper contact position on the nozzle surface in the relative movement direction. The amount of liquid discharged per unit time from at least one nozzle facing the wiper when viewed from the direction orthogonal to the nozzle surface is one upstream of the relative movement direction from the contact position. Rukoto be controlled to be larger than the discharge amount of liquid per unit time from the nozzle is preferred.

  In the liquid ejection device of the present invention, it is preferable that the liquid ejection device further includes an airflow generation mechanism that generates an airflow in a direction opposite to a relative movement direction of the wiper when the flushing operation is performed toward the wiper. .

According to the said structure, the liquid discharged from the nozzle with airflow can be made to adhere to a wiper reliably.

  Further, in the liquid ejection apparatus of the present invention, when a plurality of sheets are continuously recorded on the recording medium by the liquid ejection head, the flushing operation is performed under the control of the flushing control unit for each predetermined number of sheets. The droplets ejected from the nozzle may be attached to the wiper, and the wiping may be performed under the control of the relative movement control means.

According to the above configuration, there is no need to perform a purge every time a foreign matter such as paper dust adhering to the nozzle surface is removed during recording.

As described above, the liquid ejecting apparatus of the present invention is ejected by the flushing operation to the wiper without performing a purging operation that consumes a large amount of liquid when a predetermined time has not elapsed since the previous liquid ejection. The adhered liquid can reduce the friction between the nozzle surface and the wiper. Therefore, it is possible to reduce the liquid consumption while preventing the nozzle surface from being damaged by friction with the wiper. On the other hand, when a predetermined time has elapsed since the previous discharge of the liquid, the thickened liquid can be dissolved by executing the purge operation. In addition, since the wiping is performed simultaneously with the flushing operation in a state where the wiper is in contact with the nozzle surface, the maintenance time can be shortened compared to the case where the liquid is attached to the wiper and the wiping is performed separately. . Furthermore, by controlling the discharge amount by the flushing control means, the wiper can be sufficiently lubricated downstream of the contact position in the relative movement direction, and the liquid consumption can be suppressed upstream of the contact position in the relative movement direction. The meniscus surface formed at the discharge port of the nozzle can be adjusted.

Hereinafter, reference examples and preferred embodiments of the present invention will be described with reference to the drawings.

< Reference Example of the Present Invention >
FIG. 1 is a schematic side view showing an overall configuration of an ink jet printer according to a reference example of the present invention. FIG. 2 is a schematic plan view of a main part of the ink jet printer shown in FIG.

As shown in FIG. 1, an ink jet printer (hereinafter simply referred to as “printer”) 1 of the present reference example is a color ink jet printer including four ink jet heads 2. A paper feed tray 11 and a paper discharge tray 12 are respectively provided on the left and right sides of the printer 1 in FIG. Furthermore, a transport mechanism 13 that transports the paper P in the paper transport direction (the direction from the left to the right in FIG. 1) while facing the nozzle surface 2a that is the lower surface of the inkjet head 2 is provided. As shown in FIG. 2, the printer 1 is provided with a maintenance unit 30 for performing maintenance on the inkjet head 2. Further, as shown in FIG. 1, the printer 1 includes a control device 70 that controls the operation of the printer 1.

  In the vicinity of the paper feed tray 11, there is provided a pair of feed rollers 5 that sandwich the paper P placed on the paper feed tray 11 and feed it to the right in FIG. The paper P sent out by the feed roller pair 5 is supplied to the transport mechanism 13.

  The transport mechanism 13 includes two belt rollers 6 and 7 and an endless transport belt 8 spanned between the belt rollers 6 and 7. As shown in FIG. 1, among the belt rollers 6 and 7, the belt roller 6 located on the downstream side in the sheet conveying direction, that is, on the right side in the drawing, is rotationally driven clockwise in the drawing by the drive motor 6a. In a region surrounded by the conveyor belt 8, a substantially rectangular parallelepiped platen 15 that supports the conveyor belt 8 from the inner peripheral surface side is disposed. Further, a nip roller 4 that presses the paper P sent out from the paper feed tray 11 by the feed roller pair 5 against the transport surface 8 a that is the outer peripheral surface of the transport belt 8 is disposed at a position facing the belt roller 7.

  Further, a peeling member 14 is provided between the conveyance belt 8 and the paper discharge tray 12. The peeling member 14 is configured to peel the paper P held on the conveyance surface 8 a of the conveyance belt 8 from the conveyance surface 8 a and guide it toward the paper discharge tray 12.

  As shown in FIG. 1, the lower surface of the inkjet head 2 is a nozzle surface 2 a on which a plurality of nozzle discharge ports 10 (see FIGS. 4 and 5) are formed, and is opposed to the conveyance surface 8 a of the conveyance belt 8. ing. The four inkjet heads 2 correspond to four colors of ink (magenta, yellow, cyan, and black), respectively, and eject inks of different colors. Each inkjet head 2 has a rectangular parallelepiped shape that is long in the main scanning direction, which is a direction orthogonal to the paper transport direction in plan view. The four inkjet heads 2 are fixed to a substantially square frame 3 in plan view so that they are aligned along the paper transport direction. That is, the printer 1 is a line type printer.

  The frame 3 is supported by a frame moving mechanism 51 so as to be movable up and down. As shown in FIG. 2, the frame moving mechanism 51 is disposed on both sides of the frame 3 along the paper conveyance direction (vertical direction in the figure). Each frame moving mechanism 51 includes a drive motor 52 that is a drive source for vertical movement, a pinion gear 53 that is fixed to the shaft of each drive motor 52, a rack gear 54 that meshes with each pinion gear 53, and a pinion gear 53. And a guide 55 arranged at a position sandwiching the rack gear 54. Among these, the drive motor 52 and the guide 55 are fixed to the main body frame 1 a of the printer 1, and the rack gear 54 is erected on the frame 3.

  In this configuration, when the two drive motors 52 are synchronized and each pinion gear 53 is rotated in the forward and reverse directions, the rack gear 54 is moved in the vertical direction. As the rack gear 54 moves up and down, the frame 3 and the four inkjet heads 2 move up and down.

  Normally, the frame 3 is arranged at a printing position (position shown in FIG. 1) where the four inkjet heads 2 eject ink onto the paper P and print. At this time, a slight gap is formed between the nozzle surface 2a of the ink jet head 2 and the transport surface 8a of the transport belt 8 to be a part of the paper transport path. When the paper P transported by the transport belt 8 sequentially passes immediately below the nozzle surface 2a, ink droplets of each color are ejected from the ejection port 10 toward the upper surface of the paper P. A desired color image is formed on P. The frame 3 is moved by the frame moving mechanism 51 during maintenance of the inkjet head 2 to be described later, and is disposed above the printing position.

  As shown in FIG. 2, the frame 3 is attached with an ink absorber 19 extending in the paper transport direction. More specifically, the ink absorber 19 is attached to the side surface of the portion of the frame 3 that extends in the paper transport direction on the left side in FIG. The ink absorber 19 is for absorbing ink adhering to the wiper 45 described later, and moves up and down together with the inkjet head 2 by driving the frame moving mechanism 51.

  Next, the configuration of the inkjet head 2 will be described in more detail with reference to FIGS. FIG. 3 is a plan view of the inkjet head 2. FIG. 4 is an enlarged view of a region surrounded by a one-dot chain line in FIG. In FIG. 4, for convenience of explanation, what is to be drawn by a broken line below an actuator unit 21 to be described later (aperture 92, pressure chamber 91 and discharge port 10 to be described later) is drawn by a solid line. FIG. 5 is a partial cross-sectional view of the inkjet head 2.

  As shown in FIG. 3, the inkjet head 2 has a flow path unit 9 having a substantially rectangular shape elongated in the main scanning direction in plan view, and four trapezoidal shapes fixed to the upper surface of the flow path unit 9 in a staggered manner. Actuator unit 21 is included. More specifically, the four actuator units 21 are arranged such that the upper side (trapezoid upper base) and the lower side (trapezoid lower bottom) of the upper surface of the flow path unit 9 coincide with the longitudinal direction of the flow path unit 9, and The oblique sides of the adjacent actuator units 21 are parallel to each other and are arranged so that the positions of the flow path units 9 in the longitudinal direction are the same.

  The inkjet head 2 has a reservoir unit (not shown) that supplies ink to the flow path unit 9 to which the actuator unit 21 is fixed as described above, and a driver IC 16 that generates a drive signal that drives the actuator unit 21 (see FIG. 7) is assembled.

  As shown in FIG. 4, a plurality of discharge ports 10 arranged in a matrix form are opened in regions facing the actuator units 21 on the lower surface of the flow path unit 9. On the upper surface of the flow path unit 9, there are opened pressure chambers 91 communicating with the respective discharge ports 10 and arranged in a matrix. The pressure chamber 91 has a substantially rhombus shape with rounded corners in plan view. One actuator unit 21 is arranged so as to cover many pressure chambers 91. Here, the actuator unit 21 includes a plurality of actuators corresponding to the pressure chambers 91 and has a function of selectively giving ejection energy to the ink in the pressure chambers 91.

  Further, as shown in FIG. 3, a total of ten ink supply ports 80 are opened on the upper surface of the flow path unit 9 corresponding to the ink outflow flow paths (not shown) of the reservoir unit. Each of the ink supply ports 80 is formed so as to avoid the adhesion region of the actuator unit 21.

  As shown in FIG. 3, the flow path unit 9 includes a manifold flow path 81 communicating with the ink supply port 80, and a region branched from the manifold flow path 81 and facing the actuator unit 21. A plurality of sub-manifold channels 81a extending in the longitudinal direction are formed. Further, as shown in FIG. 5, an individual ink flow path 95 extending from the sub manifold flow path 81a to the discharge port 10 through the aperture 92 and the pressure chamber 91 is formed inside the flow path unit 9. Yes. That is, the same number of the individual ink flow paths 95 as the discharge ports 10 are formed so as to correspond to the respective discharge ports 10 (pressure chambers 91).

  Thereby, the ink from the reservoir unit is supplied to the manifold channel 81 via the ink supply port 80 and further distributed to the pressure chambers 91. When the ejection energy is selectively applied to the pressure chamber 91 by the actuator unit 21, the pressure of the ink in the pressure chamber 91 rises, and the ink is ejected from the ejection port 10 communicating with the pressure chamber 91.

  As shown in FIG. 5, the flow path unit 9 includes nine plates 82 to 90 made of a metal material such as stainless steel. By laminating these plates 82 to 90 while being aligned with each other, the through holes formed in the plates 82 to 90 are connected to each other, and the manifold channel 81, the sub manifold channel 81a, and the sub manifold channel 81a are connected in the channel unit 9. A large number of individual ink flow paths 95 are formed from the outlet of the manifold flow path 81 a to the discharge port 10 through the aperture 92 and the pressure chamber 91.

  Further, as shown in FIG. 1, the inkjet head 2 includes four ink cartridges 18 arranged in parallel in the paper conveyance direction below the conveyance mechanism 13 and a tube (not shown) via a pump 17 (see FIG. 7). ). The four ink cartridges 18 respectively correspond to four color inks (magenta, yellow, cyan, and black), and the pump 17 is disposed in the ink jet head 2 that discharges the corresponding color of the ink in the ink cartridge 18. It is for sending forcibly. Therefore, by driving the pump 17, the ink in the manifold channel 81, the sub-manifold channel 81 a, and the individual ink channel 95 is pressurized, and the air, dust, and thickened ink mixed in the inkjet head 2. It is possible to perform a purge operation for forcibly discharging foreign matters such as the ink together with the ink. The pump 17 is stopped during image formation on the paper P. The stopped pump 17 has an ink flow path formed therein so that the ink cartridge 18 and the inkjet head 2 communicate with each other.

  Next, the maintenance unit 30 will be described with further reference to FIG. FIG. 6 is a schematic side view of the maintenance unit 30. As shown in FIGS. 2 and 6, the maintenance unit 30 includes an X stage 31 that can move in the main scanning direction (X direction), and a wiping unit that can move in the paper transport direction (Y direction) on the top surface of the X stage 31. 40 and a moving tray 61 fixed to the left side surface of the X stage 31 in FIGS.

  The X stage 31 extends along the paper transport direction and is slidably supported by a pair of guide rails 32 extending in the main scanning direction in the vicinity of both ends in the paper transport direction. The extension / extension of the X stage 31 in the paper conveyance direction is equal to or longer than the length of the four inkjet heads 2 arranged in the paper conveyance direction. In addition, the X stage 31 is threadedly engaged with a ball screw 33 extending in the main scanning direction in parallel with the guide rail 32 at the lower part thereof. The drive motor 34 connected to the end of the ball screw 33 rotates the ball screw 33 so that the X stage 31 can move in the main scanning direction.

  The moving tray 61 fixed to the X stage 31 is a rectangular plate member in plan view, and supports the waste ink tray 62. Accordingly, the waste ink tray 62 can move in the main scanning direction as the X stage 31 moves. The waste ink tray 62 has a bottom surface that can be opposed to the four inkjet heads 2 in the vertical direction.

  The wiping unit 40 includes a Y stage 41, a wiper 45, a holder 46, and a discharge tray 47. The Y stage 41 is slidably supported by a pair of guide rails 42 laid on the upper surface of the X stage 31 so as to extend in the paper transport direction. Further, the Y stage 41 is screwed into a ball screw 43 extending in parallel to the guide rail 42, that is, in the paper transport direction. The drive motor 44 connected to the end of the ball screw 43 rotates the ball screw 43, so that the Y stage 41 can move in the paper transport direction. As shown in FIG. 6, the upper surface of the Y stage 41 is located above the waste ink tray 62.

  The wiper 45 is a rectangular plate member made of an elastic material such as rubber or resin for wiping off foreign matters such as ink and paper dust attached to the nozzle surface 2a. The holder 46 is fixed to the upper surface of the Y stage 41, and supports the wiper 45 so that the wiper 45 is inclined at a predetermined angle with respect to the nozzle surface 2a. The discharge tray 47 is fixed to the upper surface of the Y stage 41 together with the holder 46, and has an inclined surface that is inclined from the vicinity of the lower end of the wiper 45 toward the waste ink tray 62. As shown in FIG. 2, the wiping portion of the wiper 45 (the portion to be wiped in contact with the nozzle surface 2 a) is formed slightly longer than the width of the inkjet head 2 (length along the paper transport direction). The ink wiped off by the wiper 45 moves to the waste ink tray 62 via the discharge tray 47.

  In this way, the holder 46 that supports the wiper 45 is fixed to the Y stage 41 that can move in the paper transport direction, and the Y stage 41 is supported by the X stage 31 that can move in the main scanning direction. Therefore, the wiper 45 is movable in the paper transport direction and the main scanning direction.

  Here, the control device 70 will be described. The control device 70 is constituted by, for example, a general-purpose personal computer. Such a computer stores hardware such as a CPU, ROM, RAM, and hard disk, and various software including a program for controlling the overall operation of the printer 1 is stored in the hard disk. And these parts and 71-75 (refer FIG. 7) mentioned later are constructed | assembled by combining these hardware and software.

  As shown in FIG. 7, which is a block diagram showing a schematic configuration of the control device 70, the control device 70 includes a timer 65 in addition to the driver IC 16, the pump 17, and the drive motors 34, 44, 52, 60 described above. It is connected. In addition, the control device 70 includes a paper conveyance control unit 71, a head control unit 72 including an ink discharge control unit 72a and a purge control unit 72b, a determination unit 73, a frame position control unit 74, and an X-direction movement control unit 75a. And a wiper control unit 75 including a Y-direction movement control unit 75b.

  The paper transport control unit 71 controls the transport of the paper P by the transport mechanism 13 by controlling the drive motor 6 a that drives the belt roller 6 of the transport mechanism 13.

  The ink ejection control unit 72a of the head control unit 72 individually controls the ejection of ink from the ejection ports 10 of the plurality of nozzles of the inkjet head 2 by controlling the driver IC 16 that generates a drive signal to the actuator unit 21. To do. The ink discharge control unit 72a discharges ink droplets from the discharge port 10 based on image data supplied from the outside, whereby an image is formed on the paper P. In addition to the image formation on the paper P, the ink discharge control unit 72a discharges ink droplets from the discharge port 10 so that a flushing operation described later is performed. Further, the purge control unit 72 b drives the pump 17 to pressurize the ink in the manifold channel 81, the sub-manifold channel 81 a, and the individual ink channel 95 and discharge the ink from all the ejection ports 10. Perform a purge operation.

  The determination unit 73 determines whether or not the elapsed time counted by the timer 65 exceeds a predetermined time. Here, the timer 65 counts the elapsed time since the purge operation was executed by the previous purge control unit 72b. Note that the predetermined time serving as a determination criterion in the determination unit 73 is a time required for the ink attached to the nozzle surface 2a to thicken so that it is difficult to remove by simply wiping with the wiper 45, and the temperature, It is appropriately set depending on the humidity, ink type, and the like.

The frame position control unit 74 controls the height position of the inkjet head 2 and the ink absorber 19 fixed to the frame 3 by controlling the drive motor 52 of the frame moving mechanism 51. In this reference example , the frame 3 is arranged at four different height positions, that is, a retracted position, a wipe position, a purge position, and a printing position under the control of the frame position control unit 74.

  The wiper control unit 75 performs relative movement of the wiping unit 40 with respect to the inkjet head 2, and the X-direction movement control unit 75 a drives the ball motor 33 that extends in the main scanning direction of the maintenance unit 30. By controlling the above, the movement of the X stage 31 is controlled. Thereby, the positions of the waste ink tray 62 and the wiping unit 40 in the main scanning direction can be controlled. The Y-direction movement control unit 75b controls the movement of the Y stage by controlling the drive motor 44 that drives the ball screw 43 extending in the sheet conveyance direction of the maintenance unit 30. Thereby, the position of the wiping unit 40 in the paper conveyance direction can be controlled.

  Next, an example of a maintenance method performed in the printer 1 will be described with reference to FIGS. FIG. 8 is a flowchart showing the operation of the printer 1 during maintenance. 9 and 10 are diagrams for explaining the movement of the inkjet head 2 and the maintenance unit 30 during maintenance.

  Here, the maintenance of the ink-jet head 2 means that the viscosity of the ink-jet head 2 increased in the vicinity of the ejection port 10 that has not ejected the paper powder flying from the paper P transported by the transport mechanism 13 or the ink for a long time when printing is performed. This means a series of operations for removing ink or the like from the nozzle surface 2a. Maintenance of the inkjet head 2 is started when the inkjet printer 1 is turned on, before printing is started, or when an instruction is given from the user.

  It should be noted that before the maintenance is started, that is, when the maintenance is not performed, the maintenance unit 30 has the waste ink tray 62 and the wiping unit 40 disposed at a standby position where they do not face the nozzle surfaces 2a of the four inkjet heads 2. Yes. The standby position is a position adjacent to the left side with respect to the main scanning direction, as shown in FIG. At this time, as shown in FIG. 2, the wiping unit 40 is located in the vicinity of the inkjet head 2 located on the most upstream side in the paper conveyance direction.

  When performing maintenance in the printer 1, first, the inkjet head 2 positioned at the printing position is moved upward as shown in FIG. 9A by the control of the frame position control unit 74 (S11). More specifically, the height position of the nozzle surface 2 a of the inkjet head 2 moves to a retreat position where it is higher than the height position of the tip of the wiper 45. Next, the determination unit 73 determines whether or not a predetermined time has elapsed since the previous purge operation was executed (S12: determination step).

  If it is determined in step S12 that the predetermined time has not elapsed (S12: NO), the X stage 31 is moved rightward in FIG. 9 under the control of the X direction movement control unit 75a. The waste ink tray 62 and the wiping unit 40 are moved to a position where the wiper 45 reaches the flushing position (S13). As shown in FIG. 9A, the flushing position is a position facing the region of the nozzle surface 2a where the discharge port 10 is formed.

  Thereafter, a flushing operation for ejecting ink from the ejection port 10 is performed under the control of the ink ejection control unit 72a, and the ink is adhered to the wiper 45 (S14: liquid adhesion step). At this time, as shown in FIG. 9B, the ink ejection control unit 72a performs control so that ink is ejected only from the ejection port 10 disposed in the region facing the wiper 45 on the nozzle surface 2a. And the ink discharged from the target head which is the inkjet head 2 which opposes at this time among the four inkjet heads 2 adheres to the wiper 45. At this time, since the inkjet head 2 is disposed at the retracted position, the tip of the wiper 45 does not contact the nozzle surface 2a of the target head.

  Subsequently, under the control of the X direction movement control unit 75a, the X stage 31 is again moved rightward in FIG. 9, and the waste ink tray 62 and the wiping unit 40 are moved to the initial position (S15). As shown in FIG. 9C, the initial position is a position where the waste ink tray 62 faces the nozzle surfaces 2a of the four inkjet heads 2 and the wiper 45 does not face the nozzle surfaces 2a.

  Next, under the control of the frame position control unit 74, the inkjet head 2 is moved to a wipe position where the height position of the nozzle surface 2 a is slightly lower than the height position of the tip of the wiper 45. Further, as shown in FIG. 9D, the X stage 31 is moved toward the left in the figure under the control of the X direction movement control unit 75a. Thereby, the wiper 45 moves from the initial position to the standby position while being in contact with the nozzle surface 2a of the target head, and wipes off the foreign matter adhering to the nozzle surface 2a (S18: wiping step). At this time, the wiper 45 moves on the nozzle surface 2a in a low friction state by the ink adhered to the wiper 45 in step S14.

  On the other hand, when it is determined in step S12 that the predetermined time has elapsed (S12: YES), the X stage 31 is moved rightward in FIG. The tray 62 and the wiping unit 40 are moved to the initial position (S16). Thereafter, as shown in FIG. 10B, the inkjet head 2 is moved to a purge position below the retracted position by the control of the frame position control unit 74, and the purge operation is executed by the control of the purge control unit 72b. (S17: Purge step). At this time, the ink discharged from the ejection port 10 falls to the waste ink tray 62, and the ink dropped to the waste ink tray 62 is sucked by a pump (not shown) and stored in the waste ink tank.

  By performing the purge operation in this way, it is possible to dissolve ink that has adhered to the nozzle surface 2a and has increased in viscosity over time. Further, the nozzle surface 2a becomes wet with the ink discharged from the ejection port 10 by the purge operation.

  Next, the inkjet head 2 is moved to the wipe position under the control of the frame position control unit 74. Further, as shown in FIG. 10C, by moving the X stage 31 toward the left in the figure, the wiper 45 is moved from the initial position to the standby position while being in contact with the nozzle surface 2a of the target head. The foreign matter adhering to the nozzle surface 2a is wiped off (S18: wiping step). At this time, the wiper 45 moves on the nozzle surface 2a in a low friction state by the ink adhered to the nozzle surface 2a in step S17.

  After the wiping step, the frame position controller 74 controls the ink absorber 19 attached to the frame 3 to descend to a position where the ink absorber 19 contacts the wiper 45, thereby absorbing ink attached to the wiper 45. Absorbed by body 19.

  Subsequently, it is determined whether or not wiping of all inkjet heads 2 has been completed (S19). If it is determined that wiping of all the inkjet heads 2 has not been completed yet (S19: NO), the Y stage 41 is moved in the paper transport direction under the control of the Y-direction movement control unit 75b ( S20). More specifically, as shown in FIG. 2, the wiping unit 40 located in the vicinity of the inkjet head 2 located on the most upstream side with respect to the paper conveyance direction is the inkjet that is located second from the upstream side with respect to the paper conveyance direction. The Y stage 41 is moved so as to move to the vicinity of the head 2. Thereafter, returning to step S12, it is determined again whether or not a predetermined time has elapsed since the previous purge operation.

  On the other hand, when it is determined that the wiping of all the inkjet heads 2 has been completed (S19: YES), the maintenance is terminated.

That is, in this reference example , the target heads are sequentially set from the inkjet head 2 positioned on the upstream side in the paper transport direction, and the operations of Steps S13 to S15 or Steps 16 and 17 are repeated four times. Maintenance of the inkjet head 2 is performed.

As described above, in the maintenance method for the inkjet head 2 of the present reference example , when the determination unit 73 determines that the predetermined time has not elapsed since the previous purge operation, the ink ejected by the flushing operation is removed. A liquid adhering step for adhering to the wiper 45 and a wiping step for wiping the nozzle surface 2a by the wiper 45 are performed, and when it is determined that a predetermined time has elapsed, a purge operation for discharging ink from all the ejection ports 10 is performed. A purge step and a wiping step are performed. Therefore, when a predetermined time has not elapsed since the previous purge operation, the nozzle surface in the wiping step is not affected by the ink ejected by the flushing operation and adhered to the wiper 45 without performing the purge operation with a relatively large amount of ink used. The friction between 2a and the wiper 45 can be reduced. Therefore, ink consumption can be reduced while preventing the nozzle surface 2a from being damaged by friction with the wiper 45. On the other hand, when a predetermined time has elapsed since the previous purge operation, the thickened ink can be removed by executing the purge operation.

Further, in the maintenance method of the ink jet head 2 of the present reference example , in the liquid adhering step, the wiper 45 disposed opposite to the region where the discharge port 10 is formed on the nozzle surface 2a and spaced apart from the nozzle surface 2a is applied. Ink is deposited and then a wiping step is performed. Therefore, since the wiper 45 is brought into contact with the nozzle surface 2a after the ink is attached to the wiper 45, damage to the nozzle surface 2a can be reliably prevented. Further, even when ink of a different color from the ink ejected by the target head is attached to the wiper 45, the ink of a different color can be washed away or thinned by the ink attached before wiping. Therefore, color mixing on the nozzle surface 2a can be prevented.

<Embodiment of the present invention >
Next, referring to FIG. 11 to 13, will be described implementation of the present invention. FIG. 11 is a flowchart illustrating the operation of the printer 1 during maintenance according to the present embodiment. FIG. 12 is a diagram for explaining the movement of the inkjet head 2 and the maintenance unit 30 during the maintenance of the present embodiment. FIG. 13 is an enlarged view of the wiper 45 when wiping is performed in the present embodiment.

The main difference between the maintenance method of the present embodiment and the maintenance method of the reference example is that, in the reference example , when the determination unit 73 determines that the predetermined time has not elapsed, the wiping is performed after the liquid discharge step is performed. In this embodiment, the liquid discharging step and the wiping step are performed simultaneously. Also, as shown in FIG. 12, the printer of this embodiment is provided at a position facing the wiper 45 in the main scanning direction, and is a direction from the standby position toward the initial position (from left to right in the figure). The fan 68 for generating the airflow in the direction toward the head is provided. Further, the control device 70 includes a fan control unit 76 that controls the driving of the fan 68. Since other configurations of the printer 1 are the same as those in the reference example , the same reference numerals are given and the description thereof is omitted, and the maintenance method will be described below.

  First, as shown in FIG. 12A, the inkjet head 2 located at the printing position is moved to the retracted position (S21). Next, the determination unit 73 determines whether or not a predetermined time has elapsed since the previous purge operation was performed (S22: determination step), and when it is determined that the predetermined time has not elapsed ( (S22: NO), the wiper 45 is moved from the standby position toward the initial position (S23). Then, as shown in FIG. 12B, after the inkjet head 2 is moved from the retracted position to the wipe position, as shown in FIG. 12C, the flushing operation is performed under the control of the ink ejection control unit 72a. Then, the wiper 45 is moved to the standby position under the control of the X-direction movement control unit 75a (S24: liquid attaching step and wiping step).

  More specifically, at this time, the ink ejection control unit 72a is required to transport the paper P by the actuator drive frequency and one printing cycle (distance corresponding to the printing resolution in the sub-scanning direction (that is, the minimum dot interval)). By controlling the number of pulses during (time), as shown in FIG. 13, the movement direction of the wiper 45 (the direction from the right to the left in the figure) downstream of the contact position of the wiper 45 on the nozzle surface 2a. The discharge amount of ink per unit time from the discharge port 10 facing the wiper 45 in the direction orthogonal to the nozzle surface 2a is the unit from the discharge port 10 on the upstream side in the movement direction of the wiper 45 from the contact position. Control is performed so that the amount of ink discharged per hour is larger.

  Further, when the liquid adhering step and the wiping step are performed in step S24, the fan 68 is driven by the control of the fan control unit 76, and the direction from the standby position to the initial position as shown by the white arrow in FIG. An airflow in the direction opposite to the moving direction of the wiper 45 indicated by the black arrow is generated. Due to this air flow, the ink ejected from the ejection port 10 on the downstream side in the moving direction of the wiper 45 from the contact position of the wiper 45 is pushed toward the wiper 45 and adheres to the wiper 45. Thus, the wiper 45 moves on the nozzle surface 2a in a low friction state by the ink adhering to the wiper 45. Ink discharge from the discharge port 10 on the upstream side in the movement direction with respect to the contact position completely discharges other colors of ink and foreign matters that may enter the discharge port 10 by the wiping operation. .

On the other hand, if it is determined in step S22 that the predetermined time has elapsed (S22: YES), the purge operation is performed after the wiper 45 is moved to the initial position (S25), as in steps S16 to S18 of the reference example. Is executed (S26: purge step), and the nozzle surface 2a is wiped by the wiper 45 (S27: wiping step).

  Subsequently, it is determined whether or not wiping of all inkjet heads 2 has been completed (S28), and if it is determined that wiping of all inkjet heads 2 has not been completed (S28: NO), the Y stage 41 is moved in the paper transport direction, and the wiping unit 40 is moved to the vicinity of the adjacent inkjet head 2 (S29). Thereafter, returning to step S22, it is determined again whether or not a predetermined time has elapsed since the previous purge operation. On the other hand, when it is determined that wiping of all the inkjet heads 2 has been completed (S28: YES), the maintenance is terminated.

As described above, in this embodiment, as in the case of the reference example, it is possible to reduce ink consumption while preventing the nozzle surface 2a from being damaged by friction with the wiper 45.

  In the present embodiment, ink is attached to the wiper 45 with the wiper 45 in contact with the nozzle surface 2a, and the liquid attaching step and the wiping step are performed simultaneously. Therefore, the maintenance time can be shortened compared to the case where the liquid adhesion step and the wiping step are performed separately.

  Further, in the present embodiment, an airflow in a direction opposite to the movement direction of the wiper 45 is applied to the wiper 45 in the liquid attaching step. Therefore, the ink ejected from the ejection port 10 by the airflow can be reliably attached to the wiper 45.

  In addition, in the present embodiment, in the liquid adhesion step, the amount of ink ejected from the ejection port 10 on the downstream side in the movement direction of the wiper 45 relative to the contact position of the wiper 45 on the nozzle surface 2a is greater than the wiper position. It is larger than the discharge amount of the ink from the discharge port 10 on the upstream side of 45 in the moving direction. Therefore, the wiper 45 can be sufficiently lubricated downstream of the contact position in the movement direction. Further, on the upstream side in the movement direction from the contact position, the meniscus surface formed in the nozzle outlet 10 can be adjusted while suppressing ink consumption.

  The preferred embodiments of the present invention have been described above. However, the present invention is not limited to the above-described embodiments, and various design changes can be made as long as they are described in the claims. Is.

For example, in the form of implementation described above, in the liquid deposition step, but the moving direction of the wiper 45 has been described for the case of generating the opposite direction of airflow, the airflow may not be generated.

In addition, in the embodiments described above in Example及BiMinoru facilities, at power-on of the ink jet printer 1, before starting printing, the case has been described where the maintenance of the inkjet head 2, for example, when receiving an instruction from the user is performed The maintenance is not limited to such a case. That is, for example, when a plurality of sheets are continuously printed on the paper P, maintenance may be performed every predetermined number of sheets. In this case, a counter that counts the number of sheets P to be printed continuously is further provided, and maintenance is performed based on the count value by the counter. According to this, when printing on a large number of sheets P continuously, a large amount of paper dust from the sheet P adheres to the nozzle surface 2a, and thus wiping of the nozzle surface 2a is required. There is no need to run. Therefore, ink consumption can be reduced.

  In the maintenance method of this embodiment, all the inkjet heads 2 are targeted for wiping by the wiper 45, but the above-described maintenance process may be performed on the inkjet heads 2 designated in advance.

1 is a schematic side view illustrating an overall configuration of an inkjet printer according to a reference example of the present invention. It is a schematic plan view of the principal part of the inkjet printer shown in FIG. It is a top view of the inkjet head shown in FIG. It is an enlarged view of the area | region enclosed with the dashed-dotted line of FIG. FIG. 4 is a partial cross-sectional view of the ink jet head shown in FIG. 3. It is a schematic side view of the maintenance unit shown in FIG. It is a block diagram which shows schematic structure of the control apparatus shown in FIG. 2 is a flowchart showing an operation of the printer when maintenance is performed in the ink jet printer shown in FIG. 1. It is a figure for demonstrating a motion of the inkjet head and a maintenance unit at the time of the maintenance in the inkjet printer shown in FIG. 1 (when predetermined time has not passed). It is a figure for demonstrating a motion of the inkjet head and a maintenance unit at the time of the maintenance in the inkjet printer shown in FIG. 1 (when predetermined time has passed). 6 is a flowchart illustrating the operation of the printer during maintenance according to the embodiment of the present invention . It is a figure for demonstrating a motion of the inkjet head and the maintenance unit at the time of the maintenance of embodiment of this invention . It is an enlarged view of a wiper when wiping is performed in the embodiment of the present invention .

Explanation of symbols

1 Inkjet printer (liquid ejection device)
2 Inkjet head (liquid discharge head)
2a Nozzle surface 10 Discharge port 17 Pump (pressure application mechanism)
21 Actuator unit 33 Ball screw (relative movement mechanism)
34 Drive motor (relative movement mechanism)
45 wiper 51 frame moving mechanism (orthogonal moving mechanism)
68 Fan (Airflow generation mechanism)
73 Judgment Unit (Judgment Means)
72a Ink ejection control unit (flushing control means)
72b Purge control unit (pressure application control means)
74 Frame position control unit (orthogonal movement control means)
75a X direction movement control unit (relative movement control means)

Claims (4)

A liquid discharge head having a nozzle surface on which discharge ports of a plurality of nozzles are formed and an actuator for generating discharge energy for discharging liquid from the nozzle;
A wiper for wiping the nozzle surface;
Determining means for determining whether or not a predetermined time has elapsed since the previous discharge of the liquid from the nozzle;
Flushing control means for controlling driving of the actuator so that a flushing operation for discharging droplets from the nozzle is performed;
A relative movement mechanism for relatively moving the liquid discharge head and the wiper along the nozzle surface while facing the wiper and the nozzle surface;
Relative movement control means for controlling the driving of the relative movement mechanism;
A pressure application mechanism for applying pressure from the outside to the liquid in the liquid discharge head;
Pressure application control means for controlling the drive of the pressure application mechanism so as to perform a purge operation in which liquid is discharged from all the nozzles,
When the constant time Tokoro by said determining means is determined not to be passed in a state where the wiper is brought into contact with the nozzle surface, by performing the flushing operation by the control of the flushing control means, In the state where the liquid droplets discharged from the nozzle are attached to the wiper, and the wiper is in contact with the nozzle surface, the flushing operation is performed by the control of the flushing control unit, and at the same time, by the relative movement control unit Wiping to wipe the nozzle surface is performed by relatively moving the liquid discharge head and the wiper. When it is determined that the predetermined time has elapsed, the purge operation is performed under the control of the pressure application control unit. after, we had row the wiping by the control of the relative movement control means,
The flushing control means is on the downstream side of the wiper relative movement direction with respect to the liquid ejection head from the contact position of the wiper on the nozzle surface and faces at least the wiper when viewed from a direction orthogonal to the nozzle surface. The liquid discharge amount per unit time from the one nozzle is larger than the liquid discharge amount per unit time from the one nozzle located upstream in the relative movement direction from the contact position. A liquid ejecting apparatus, characterized by being controlled . The flushing control means controls either the drive frequency of the actuator or the number of pulses in one printing cycle, so that the flushing control means is located downstream of the wiper contact position on the nozzle surface in the relative movement direction. The amount of liquid discharged per unit time from at least one nozzle facing the wiper when viewed from the direction orthogonal to the nozzle surface is one upstream of the relative movement direction from the contact position. The liquid ejection apparatus according to claim 1, wherein the liquid ejection apparatus is controlled so as to be larger than a liquid ejection amount per unit time from the nozzle. According to claim 1 or 2, characterized in that it further comprises an airflow generating mechanism that generates toward the opposite direction of air flow to the wiper the previous SL-relative movement direction when the flushing operation is carried out Liquid ejection device. When a plurality of sheets are continuously recorded on the recording medium by the liquid ejection head, the droplets ejected from the nozzles are discharged by performing the flushing operation under the control of the flushing control unit for each predetermined number of sheets. is deposited on the wiper, further apparatus according to any one of claims 1 to 3, characterized in that the wiping by the control of the relative movement control means.

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